Stability of networked control systems with multi-step delay based on time-division algorithm

A new control mode is proposed for a networked control system whose network-induced delay is longer than a sampling period. A time-division algorithm is presented to implement the control and for the mathematical modeling of such networked control system. The infinite horizon controller is designed, which renders the networked control system mean square exponentially stable.Simulation results show the validity of the proposed theory.

On Fault Diagnosis of Rotating Machinery Using Wavelet Time-division Scale Level Moment

Based on an in-depth study of wavelet gray moment, we proposed a concept of a time-division scale level moment and gave the specific definition; ulteriorly, we discussed the factors which affected the fault diagnosis ability of a time-division scale level moment. The analysis results in the caculation of six typical fault signals show that the time-division scale level moment can be used to display the detailed information of a wavelet gray level image, extract the signal＇s characteristics effectively, and distinguish the vibration fault. Compared to the method of a wave gray moment vector, the method mentioned in this paper can provide higher calculation speed and higher capacity of fault identification, so it is more suitable for online fault diagnosis for rotating machinery.

Downlink/Uplink Identification of Time-Division Duplexing-OFDMA Systems for Cognitive Radios

When coexisting with dual-link primary systems,secondary systems in cognitive radios should first distinguish between the primary downlinks and uplinks in order to efficiently explore their respective spectrum opportunities.Because of the assumptive prior knowledge about the time-frequency locations of primary downlinks and uplinks,this procedure is usually not considered in the design of cognitive radios.In this paper,a cooperative method is proposed for the downlink/uplink identification of time-division duplex-based orthogonal frequency-division multiple access systems.In this method,the power level of the primary link is extracted as the key feature,which also contributes to the subsequent cognitive behaviours.The effects of the primary and secondary systems and the effects of the detection parameters on the identification accuracy are all analysed in detail.The simulation results show that the proposed method can identify the primary links precisely and quickly with low complexity.

Simple Closed-Loop Method to Compensate Interference Asymmetry in Time-Division Duplex MIMO-OFDM Systems

In wireless communications systems with time-division duplex (TDD) deployment, channel reciprocity and symmetric interference between transmitter and receiver sides are two widely-adopted assumptions for the design of optimal adaptation transmission mode. However, in practice, there is an undesirable but non-negligible effect, namely the asymmetric interference, that makes the assumptions no longer valid. In this paper, a simple closed-loop feedback method of compensating interference asymmetry in TDD multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system is proposed. The system makes the estimated interference at transmit-side be able to track the instantaneous receive-side interference dynamically. The proposed method maintains constant frame error rate (FER) by adopting adaptive modulation coding (AMC) and power loading. The final simulations have verified the effectiveness of the new method.

Fast time-division color electroholography using a multiple-graphics processing unit cluster system with a single spatial light modulator

We demonstrate fast time-division color etectroholography using a multiple-graphics-processing-unit （GPU） cluster system with a spatial light modulator and a controller to switch the color of the reconstructing light. The controller comprises a universal serial bus module to drive the liquid crystal optical shutters. By using the controller, the computer-generated hologram （CGH） display node of the multiple-GPU cluster system synchronizes the display of the CGH with the color switching of the reconstructing light. Fast time-division color electroholography at 20 fps is realized for a three-dimensional object comprising 21,000 points per color when 13 GPUs are used in a multiple-GPU cluster system.

Polarization-Insensitive All-Optical Time-Division Demultiplexer Constructed with a Nonlinear Loop Interferometer

A polarization-insensitive 40-Gb/s time-division demultiplexer was demonstrated in a polarization-diversity loop configuration. The power penalty was measured to be 2.3 dB at a bit error rates of 10-9 for 10 Gb/s output signals.

A Two-Stage Method for Routing in Field-Programmable Gate Arrays with Time-Division Multiplexing

Emerging applications widely use field-programmable gate array(FPGA)prototypes as a tool to verify modern very-large-scale integration(VLSI)circuits,imposing many problems,including routing failure caused by the limited number of connections among blocks of FPGAs therein.Such a shortage of connections can be alleviated through time-division multiplexing(TDM),by which multiple signals sharing an identical routing channel can be transmitted.In this context,the routing quality dominantly decides the performance of such systems,proposing the requirement of minimizing the signal delay between FPGA pairs.This paper proposes algorithms for the routing problem in a multi-FPGA system with TDM support,aiming to minimize the maximum TDM ratio.The algorithm consists of two major stages:(1)A method is proposed to set the weight of an edge according to how many times it is shared by the routing requirements and consequently to compute a set of approximate minimum Steiner trees.(2)A ratio assignment method based on the edge-demand framework is devised for assigning ratios to the edges respecting the TDM ratio constraints.Experiments were conducted against the public benchmarks to evaluate our proposed approach as compared with all published works,and the results manifest that our method achieves a better TDM ratio in comparison.

A TDMA Approach for OFDM-Based Multiuser RadCom Systems

This paper is focused on the multiuser implementation of fusion of radar and communication(RadCom)in internet-of-vehicles(IoV)scenarios.Traditional time-division multiple access(TDMA)technology degrades the velocity detection performance of orthogonal frequency-division multiplexing(OFDM)-based RadCom systems.We propose a new TDMA approach for OFDM-based RadCom systems,where multiuser communication and radar detection are completed synchronously.We consider a continuous-wave TDMA OFDM structure in which random user data or Zadoff-Chu(ZC)sequences are transmitted in one symbol duration to ensure detection performance.As an application of interference cancellation method,user data demodulation and environment sensing can be simultaneously accomplished by our proposed approach.We carry out numerical evaluation and show wireless communication and radar detection performance over the continuous-wave TDMA OFDM-based RadCom approach.

Robust Beamforming Under Channel Prediction Errors for Time-Varying MIMO System

The accuracy of acquired channel state information(CSI)for beamforming design is essential for achievable performance in multiple-input multiple-output(MIMO)systems.However,in a high-speed moving scene with time-division duplex(TDD)mode,the acquired CSI depending on the channel reciprocity is inevitably outdated,leading to outdated beamforming design and then performance degradation.In this paper,a robust beamforming design under channel prediction errors is proposed for a time-varying MIMO system to combat the degradation further,based on the channel prediction technique.Specifically,the statistical characteristics of historical channel prediction errors are exploited and modeled.Moreover,to deal with random error terms,deterministic equivalents are adopted to further explore potential beamforming gain through the statistical information and ultimately derive the robust design aiming at maximizing weighted sum-rate performance.Simulation results show that the proposed beamforming design can maintain outperformance during the downlink transmission time even when channels vary fast,compared with the traditional beamforming design.

光交换的原理与实现

本文详细介绍了空分、时分、波分以及各种复合形式光交换的概念和所需关键器件的原理，给出了在目前技术条件下各种光交换单元的实现方案，并比较了它们的难易程度和优缺点．

Two-Codebook-Based Cooperative Precoding for TDD-CoMP in 5G Ultra-Dense Networks

In ultra-dense networks （UDN）, the local precoding scheme for time-division duplex coordinated multiple point transmission （TDD-CoMP） can have a good performance with no feedback by using reciprocity between uplink and dovallink. However, if channel is time-varying, the channel difference would cause codeword mismatch between transmitter and receiver, which leads to performance degradation. In this paper, a linear interpolation method is proposed for TDD-CoMP system to estimate the uplink channel at the receiver, which would reduce the channel difference caused by time delay and decrease the probability of codeword mismatch between both sides. Moreover, to mitigate severe inter-cell interference and increase the coverage and throughput of celledge users in UDN, a two-codebook scheme is used to strengthen cooperation between base stations （BSs）, which can outperform the global precoding scheme with less overhead. Simulations show that the proposed scheme can significantly improve the link performance compared to the global precoding scheme.

Adaptive blind gain correction of time-interleaved ADCs forwide-band communication applications

High spectral efficiency is essential in design of multimedia communication systems such as L-band mobile in addition to various requirements of transmission quality. Time-interleaved A/D converter （TI-ADC） is an effective candidate to implement wide-band ADC with relatively slow circuits accounting for digital spectrum management. However, practical performance of TI-ADC is largely limited because of mismatches between different channels originated from manufacturing process variations. In this paper, a blind adaptive method is proposed to correct gain mismatch errors in TI-ADC, and it is verified through simulations on a two-channel TI-ADC. In proposed method, gain mismatch error is estimated and corrected in an adaptive scheme. Proposed compensated T1-ADC architecture is structurally very simple and hence suitable for realiza- tion in integrated circuits. Besides, proposed digital compensation algorithm not only is computationally efficient but also provides an improvement of 32.7 dB in the performance of two-channel TI ADC.

Higher Speed Passive Optical Networks for Low Latency Services

Latency sensitive services have attracted much attention lately and imposedstringent requirements on the access network design. Passive optical networks (PONs) providea potential long-term solution for the underlying transport network supporting theseservices. This paper discusses latency limitations in PON and recent progress in PONstandardization to improve latency. Experimental results of a low latency PON system arepresented as a proof of concept.

厌氧折流板反应器处理养殖废水的研究

用单侧进水和分区进水厌氧折流板反应器对养猪废水的处理进行对比研究,分区进水反应器前两个隔室进水比为6∶4.当COD浓度在4 000mg/L^5 000mg/L左右时,水力停留时间12h,有机负荷最高可达10kg COD/(m3.d),单侧进水COD去除率为35%,分区进水COD去除率维持在40%.实验研究表明,分区进水厌氧折流板反应器对养猪废水COD去除率高于单侧进水,不同进水方式ABR对NH3-N无去除,出水NH3-N浓度高于进水.

100-112 Gbit/s complete ETDM systems based on monolithically integrated transmitter and receiver modules

Traditional intensity modulated two-level electrical time-division multiplexing （ETDM） transmission systems working at 100 -112 Gbit/s were investigated. The complete ETDM systems based on monolithically integrated transmitter and receiver modules were demonstrated with biterror-rate （BER） performance of 10-s at 107 Gbit/s, and near error-free standard forward error correction （FEC） threshold （2 × 10 -3） at 112 Gbit/s. The experiment results showed that directly modulated high-speed ETDM transmission systems with the symbol rates at 100 Gbaud and beyond were promising candidate for cost-effective 100 GbE applications and might be a preform of the next generation of Terabit/s Ethernet.

MUSIC-Based Pilot Decontamination and Channel Estimation in Multiuser Massive MIMO System

This paper addresses the problem of channel estimation in a multiuser multi-cell wireless communications system in which the base station(BS)is equipped with a very large number of antennas(also referred to as"massive multiple-input multiple-output(MIMO)").We consider a time-division duplexing(TDD)scheme,in which reciprocity between the uplink and downlink channels can be assumed.Channel estimation is essential for downlink beamforming in massive MIMO,nevertheless,the pilot contamination effect hinders accurate channel estimation,which leads to overall performance degradation.Benefitted from the asymptotic orthogonality between signal and interference subspaces for non-overlapping angle-of arrivals(AOAs)in the large-scale antenna system,we propose a multiple signals classification(MUSIC)based channel estimation algorithm during the uplink transmission.Analytical and numerical results verify complete pilot decontamination and the effectiveness of the proposed channel estimation algorithm in the multiuser multi-cell massive MIMO system.

地震数据时频分析与分频处理

在地震数据处理过程中,时频分析技术可较好地描述信号和噪声的频率随时间变化的规律,即时频分析可以细致地刻画数据中各类波的时频结构和性质,其重要性在于能直观地识别、检测和分类数据,因此,可采取有针对性的措施,以提高每一个步骤的处理精度。简述了时频分析的方法原理,介绍了适应于地震数据分析的窗函数的选取方法,并展示了分频噪声压制的应用效果,说明分频处理是提高数据处理保真度的有效方法。

时频分析在地震剖面数据的分频显示中的应用

时频分析技术是一种十分有效的地震资料处理技术。阐述了短时傅立叶变换的概念及性质。介绍了短时傅立叶变换在地震数据处理中的效果。利用自编的Matlab程序对地震数据进行短时傅立叶变换,生成分频率数据体;然后用Surfer软件数据处理与显示功能来实现地震剖面的分频显示。

大连快轨3号线续建工程区间信号设计

研究目的:通过对大连快轨3号线续建工程线路平、纵断面条件分析,结合线路通过能力要求和信号设备的类型,按照线路运量要求进行列车模拟牵引计算,通过模拟牵引计算结果,设计出适合大连快轨3号线续建工程列车安全运行的运输能力和合理的区间分界标位置。研究结论:通过模拟牵引计算,列车最高运行速度为79 km/h时,最大制动距离为657 m,考虑必要的安全距离,本线最大的闭塞分区长度取700 m即可满足要求。在开发区站附近,考虑列车的折返要求和列车运行速度,最小闭塞分区长度取200 m即可满足要求。在采用固定闭塞方式条件下,信号设备速度码分级应与列车运行速度相一致,不能限制列车的正常运行,从而提高列车的运行速度。

A topology-transparent MAC scheduling algorithm with guaranteed QoS for multihop wireless network

Due to its character of topology independency, topology-transparent medium access control (MAC) scheduling algorithm is very suitable for large-scale mobile ad hoc wireless networks. In this paper, we propose a new topologytransparent MAC scheduling algorithm, with parameters of the node number and the maximal nodal degree known, our scheduling algorithm is based on a special balanced incomplete block design whose block size is optimized by maximizing the guaranteed throughput. Its superiority over typical other scheduling algorithms is proven mathematically with respect to the guaranteed throughput, the maximal transmission delay, and also the minimal transmission delay. The effect of inaccuracy in the estimation of the maximal nodal degree on the guaranteed throughput is deduced mathematically, showing that the guaranteed throughput decreases almost linearly as the actual nodal degree increases. Further techniques for improving the feasibility of the algorithm, such as collision avoidance, time synchronization, etc., are also discussed.